#include <REGX52.H>
void Delay1ms(unsigned int xms)		//@12.000MHz
{
	unsigned char i, j;
		while(xms--)
		{ i = 2;
			j = 239;
			do
			{
				while (--j);
			} while (--i);
		}
}

	void main ()
	{    unsigned char a ;
		while(1)
		{
			if(P3_0==0)
			{
				Delay1ms(20);
			  while(P3_0==0);
				Delay1ms(20);
				a++;
				P2=~a++;
				
				
			
			}
		
		}
	
	
	}
